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[209.85.220.65]) by mx.google.com with SMTPS id l96sor6818225plb.68.2019.05.31.07.29.22 for (Google Transport Security); Fri, 31 May 2019 07:29:22 -0700 (PDT) Received-SPF: pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b="sQG2/gyF"; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=evy368hWiI+gBYUbtpZ/Z/NwaFGt0gP/Ku0Se7jRDIs=; b=sQG2/gyFbhvQgnnYVMoq8Kda68VVztjS6NpVGpn+TJ/0x1CnUPLFGI7CfwhDx4Acpv +b2SfJPlJiXKHOPX0vraeScgQBz7b7Nl6PyJKu6e145lCoysI0y6J5myuuCSNlucfPw4 OziFqAsvBRMmxzPBSxXT6y9ZOWT1qftFo2UhubNHkIM+xAKIuSxRN1IDkqLlB5D+IEDh 9Lbkk942zOUUnqGLz1d6wvbTAZV2QEf8AYds1RPyvHK7XFYBgL+gUTiPMyMH1+mL85z0 rHLvvgL9h/d8SCsWwDzjC1mOEMEITHFigTDJGZoVkvgiZ6th+Bg/aZrVlKENNn6Dl+G9 3qvw== X-Google-Smtp-Source: APXvYqzZNq7ZmlghEU+anyWYnwjjhfBSO821IIVYI0unmJhzupp13rZUJ7jf2s8ZHPUTRKkSRgHsOXgkfcRcIwbO8eo= X-Received: by 2002:a17:902:8609:: with SMTP id f9mr9244481plo.252.1559312961740; Fri, 31 May 2019 07:29:21 -0700 (PDT) MIME-Version: 1.0 References: <20190517144931.GA56186@arrakis.emea.arm.com> <20190521182932.sm4vxweuwo5ermyd@mbp> <201905211633.6C0BF0C2@keescook> <6049844a-65f5-f513-5b58-7141588fef2b@oracle.com> <20190523201105.oifkksus4rzcwqt4@mbp> <20190524101139.36yre4af22bkvatx@mbp> <20190530171540.GD35418@arrakis.emea.arm.com> In-Reply-To: <20190530171540.GD35418@arrakis.emea.arm.com> From: Andrey Konovalov Date: Fri, 31 May 2019 16:29:10 +0200 Message-ID: Subject: Re: [PATCH v15 00/17] arm64: untag user pointers passed to the kernel To: Catalin Marinas Cc: Kees Cook , Evgenii Stepanov , Linux ARM , Linux Memory Management List , LKML , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Dmitry Vyukov , Kostya Serebryany , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy , Elliott Hughes , Khalid Aziz Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, May 30, 2019 at 7:15 PM Catalin Marinas wrote: > > On Tue, May 28, 2019 at 04:14:45PM +0200, Andrey Konovalov wrote: > > Thanks for a lot of valuable input! I've read through all the replies > > and got somewhat lost. What are the changes I need to do to this > > series? > > > > 1. Should I move untagging for memory syscalls back to the generic > > code so other arches would make use of it as well, or should I keep > > the arm64 specific memory syscalls wrappers and address the comments > > on that patch? > > Keep them generic again but make sure we get agreement with Khalid on > the actual ABI implications for sparc. OK, will do. I find it hard to understand what the ABI implications are. I'll post the next version without untagging in brk, mmap, munmap, mremap (for new_address), mmap_pgoff, remap_file_pages, shmat and shmdt. > > > 2. Should I make untagging opt-in and controlled by a command line argument? > > Opt-in, yes, but per task rather than kernel command line option. > prctl() is a possibility of opting in. OK. Should I store a flag somewhere in task_struct? Should it be inheritable on clone? > > > 3. Should I "add Documentation/core-api/user-addresses.rst to describe > > proper care and handling of user space pointers with untagged_addr(), > > with examples based on all the cases seen so far in this series"? > > Which examples specifically should it cover? > > I think we can leave 3 for now as not too urgent. What I'd like is for > Vincenzo's TBI user ABI document to go into a more common place since we > can expand it to cover both sparc and arm64. We'd need an arm64-specific > doc as well for things like prctl() and later MTE that sparc may support > differently. OK. > > -- > Catalin